Methyl substituted oxobicyclo-4,4,0-decane derivatives, process for preparing same and organoleptic uses thereof

A process for forming at least one compound defined according to the structure:

• ##STR457## said reaction being carried out in the presence of a solvent selected from the group consisting of benzene, tetrahydrofuran and diethyl ether;
• wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represents methyl or hydrogen;
• and wherein the dashed line represents a carbon-carbon single bond or a carbon-carbon double bond comprising the step of reacting a compound having the structure:
• ##STR458## with a compound having the structure:
• CH.sub.3 --M(R.sub.7).sub.n
• wherein M represents MgX, Na, K, Li, Cd, Mg or Zn;
• wherein R.sub.7 represents lower alkyl;
• wherein M is Cd, Mg or Zn when n=1, and M is MgX, Na, K or Li, when n=0, the mole ratio of organometallic compound having the structure:
• CH.sub.3 --M(R.sub.7).sub.n :
• compound having the structure:
• ##STR459## is about 1:1, the reaction being carried out from about -5.degree. C. up to about 40.degree. C. in order to form a compound having the structure:
• ##STR460## hydrolyzing the compound having the structure:
• ##STR461## using a mineral acid selected from the group consisting of sulfuric acid, phosphoric acid and paratoluene sulphonic acid at a temperature of between 0.degree. and 20.degree. C.;
• and then isolating the compound having the structure:
• ##STR462## from the reaction mass.